This study aims to extend cytogenetic techniques for the analysis of chromosomal aberrations by further use of high resolution electron microscopy. Light microscopically identified abnormalities will be transferred to the electron microsocpe for structural and quantitative analysis. The chromosomal aberration will be incurred by ionizing radiation, chemicals and viruses. Comparative observations will be drawn from the effects of these mutagenic agents. It is anticipated that the proposed study will afford the examination of chromosomal anomalies at the fiber level and render significant structural information on heretofore ill-defined aberrations as chromosome and chromatid breaks, achromatic gaps and chromosome pulverization.